It is stated in U.S. Pat. No. 4,152,231 to St. Claire et al that adhesives based on hydrogenated monoalkenylarene-diene block copolymers have relatively low service temperature, poor ultraviolet resistance, poor solvent resistance and high viscosity.
It was proposed in the '231 patent that a composition based on 100 parts by weight linear or radially conjugated diene polymers which are homopolymers of C4 to C12 conjugated dienes and copolymers with two or more C4 to C12 conjugated dienes and their halogenated derivatives tackified with from 0 to 254 parts by weight tackifier resin could be enhanced with respect to shear strength, UV resistance and solvent resistance by radiation curing in the presence of 1 to 100 parts by weight di to tetra-functional acrylate or methacrylate selected from acrylic and methacrylic esters of polyols. Conventional plasticizer compounds, oils, liquid resins, fillers and anti-oxidants and the like could be tolerated.
The compositions were disclosed to be curable by exposure to high-energy radiation such as electron-beam (EB) radiation or ultraviolet (UV) radiation. Electron-beam was stated to be preferred since it enabled crosslinking of compositions based on either unhydrogenated or hydrogenated polymers while UV radiation could only initiate crosslinking with unhydrogenated polymers.
A photosensitizer is disclosed as necessary to speed ultraviolet crosslinking reactions.
Polythiols have been proposed for use in the polymerization of and/or crosslinking of polyols. Applications have ranged from the production of printing plates, photoresists, plastic bottle coatings, lacquers, cured elastomers and natural rubbers, water-coating and other compositions.
U.S. Pat. No. 3,920,877 to Barber et al discloses that the semi-solid pressure-sensitive polythiolether polymer systems may be formed by curing of liquid components using UV or beta radiation. The polymers are normally tacky and when fully cured are useful as pressure-sensitive adhesives. They are characterized as being comprised of liquid polyene compositions containing at least two unsaturated carbon to carbonyl bonds per molecule located terminally or pendant to the main chain backbone and cured to odorless tacky elastomer products with polyols under ambient conditions in the presence of a free-radical generator. The formed adhesives are useful for adhesive tapes, labels, tiles, coverings and the like.